1. Field of Invention
This invention relates to a fluid pressure sensor, and more particularly to a pressure sensor which can be used internal to the human body.
2. Description of Prior Art
Often intracranial pressure measurements and evaluations must be made at regular intervals over a long period of time, and in many instances for years. One measurement technique is the employment of a special type of needle which is inserted into the cranium. This approach is not only unpleasant but also introduces the danger of bacteria and hemorrhaging.
Other implantable pressure sensing devices have been suggested, but many of these prior art devices require contacts or probes to be connected to the sensing device during pressure measurements. Improvements over the contact or probe type of sensors suggest the implantation of an intracranial pressure sensing device devoid of probes or contacts during sensing. One known device employs a battery operated pressure related transmitting implanted device whose signal is sensed by telemetry techniques. However, this device has a relatively short lifetime since it requires batteries and moreover is size limited as it requires a mechanical switch.
Careful consideration also must be given to materials used to form the sensor housing in order to minimize tissue reactivity. The material must be safe to the human patient and also impervious to moisture. Entry of moisture or liquid into the electrical portions of the sensor deleteriously affect its operation.